1. Field of the Invention
The present invention relates to a substrate processing apparatus used for processing such as plasma CVD (Chemical Vapor Deposition), low pressure CVD, metal CVD, insulating film CVD, ion implantation and etching.
2. Description of the Background Art
For semiconductor manufacturing apparatuses for processing semiconductor substrates such as silicon wafers as one type of the substrate processing apparatus, various susceptors (ceramics module) for mounting and heating a wafer have been proposed, some of which have been already practically used.
For example, Japanese Patent Laying-Open No. 4-78138 proposes a semiconductor wafer heating apparatus such as shown in FIG. 8.
Referring to FIG. 8, a semiconductor wafer heating apparatus 101 has a T-shaped cross section, and in which a disk-shaped heater portion 102 and a columnar support portion 105 are integrated. Disk-shaped heater portion 102 is formed of ceramic, and a resistance heater 103 is embedded spirally therein.
Columnar support portion 105 is joined to a center of portion on the rear surface of a wafer heating surface 102a. An O-ring 109 is provided between an outer circumferential surface of columnar support portion 105 and a chamber 104 for air tight sealing. A thermocouple 111 and two electrodes 103a are embedded in disk-shaped heater portion 102 and columnar support portion 105, and taken out from chamber 104 through an upper end surface of columnar support portion 105.
In such heating apparatus 101, when power is supplied to an end portion of resistance heater 103 through electrode 103a, resistance heater 103 generates heat, and wafer heating surface 102a is heated.
According to this publication, beating apparatus 101 can prevent contamination as experienced by a metal heater, does not suffer from unsatisfactory thermal efficiency as in an indirect heating method, and does not suffer from the problem of thermal adhesion onto an infrared transmission window. Further, in the heating apparatus, corrosion of electrodes as well as discharge and leakage between electrodes or the electrode housing can also be prevented.
However, in heating apparatus 101 having the above described structure, it is necessary to attach columnar support portion 105 to disk-shaped heater portion 102 in which resistance heater 103 is embedded. This results in a complicated structure and hence significantly increases cost. Further, as columnar support portion 105 supports disk-shaped heater portion 102, it must have a large cross sectional area and large thermal capacity. Thus, as the heat generated by resistance heater 103 is transferred to columnar support portion 105, thermal uniformity of wafer heating surface 102a of disk-shaped heater portion 102 is made unstable.
Further, in order to attain air tight seal using O-ring 109 at the contact portion between columnar support portion 105 and chamber 104, it is necessary to lower the temperature to be 200° C. or lower. Thus, the length of columnar support portion 105 becomes 200 mm or longer, and the height of the apparatus cannot be made smaller.
Further, in order to support disk-shaped heater 102, in most cases the columnar support portion 105 is attached to the central portion on the rear surface of disk-shaped heater portion 102. This poses restrictions on the position of mounting power supply conductive members or thermocouple electrically connected to resistance heater 103.